Download Seasons and Weather

Seasons and
Weather
Chapter 3:
Section 1
A Human Perspective
• The smell of thousands of decaying corpses
hung in the air in what was once the thriving
seaport of Galveston, Texas. The day before,
winds estimated at 130 miles per hour roared
through the city. A Storm surge of seawater
more than 15 feet high pushed a wall of debris
across the island of Galveston. Through this
turmoil, Isaac Cline’s family huddled in their
home. A trolley trestle rammed the house until
at last it collapsed, and the waves poured in.
Cline survived, but some of his family did not.
With a toll of 8,000 human lives, the “Great
Galveston Hurricane” would be the deadliest
hurricane to hit the United States. The storm
date was August 8, 1900.
Seasons
• The seasons are related to the
earth’s tilts and revolution.
• Some locations receive more direct
sun rays because of the earth’s tilt.
• Revolution: one complete orbit
around the sun. (365 ¼ days)
• Rotation: earth makes one rotation
every 24 hrs.
The causes of the changing season
on the earth?
• Solstice occur around
December 22 & 23 &
around June 21 or 22.
• Summer, sun hit
directly at Tropic of
Cancer.
• Winter, sun hit directly
at the Tropic of
Capricorn.
• 24 hrs. of light or
darkness in Arctic
Circle or Antarctic
Circle.
• Equinoxes is Latin for
“equal night”
• Poles are not pointed
toward or away from
the sun & both
hemispheres receive
exactly 12 hrs of
sunlight.
• Spring, March 21, is
called Vernal Equinox.
Northern Hemisphere.
• Fall, September 21, is
called Autumnal
Equinox. Northern
Hemisphere.
Weather
• Weather and climate are often
confused.
• Weather is the condition of the
atmosphere at a particular location
and time.
• Climate is the term for weather
conditions at a particular location
over a long period of time.
What causes the weather?
• The amount of solar energy received by an
area by its location to the earth position and
sun.
• Water Vapor: it determine whether there will
be precipitation. (rain, sleet, snow, or hail)
• Cloud cover will hold water vapor.
• Landforms & bodies of water: Water heats
slowly but can retain heat, & land heat rapidly
but loses heat quickly.
• Elevation: As elevation increases, the air
becomes thinner and loses is ability to hold
moisture.
• Air movement: winds move the air and the
solar energy and moisture that it holds.
Precipitation: water vapor in
the air (rain)
• Convectional: hot climates, the sun
heats the air, and warm air rises
• Orographic: Associated in mts. Areas.
Mountain block the passage of the air
and cause it to rise. Windward receives
the rain & on the leeward side is called
rain shadow & does not received any
water only dry air.
• Frontal: Mid-Latitude,cold dense air
pushes up warm, light air causing
precipitation.
Convectional
Frontal
Weather Extremes: as air moves across
the earth, warm and cool air collides
with each other and they create
weather.
• Hurricanes
• Tornadoes
• Blizzards
• Droughts
• Floods
Hurricanes
• They are storms that
form over warm,
tropical ocean water.
• Different names:
• In Asia:typhoons,
• Tropical cyclones
• Australia: willy-willies
• Philippines: baguios
• Mexico:Chubascos
• Different categories.
• Stage 1 is just above 75
miles to stage 5, over
150 miles.
• Danger: storm surges,
flooding & high winds.
• 25 to 30 per yr., but
only 3 to 6 make
landfall.
Tornadoes
• Or a twister, is a
powerful funnel-shaped
column of spiraling air.
• They form quickly &
without warning.
• Born from strong
thunderstorms, winds
swirl counter-clockwise,
& winds may reach
speed of 300 miles per
hour.
• Usually small diameter
& will last only a few
minutes, but they have
been know to be as
wide as a mile & last for•
hours.
• 700 tornadoes each yr.
This is the oldest known photo of
a tornado. It was taken on
August 28, 1884 near Howard, South
Dakota. The name of the
photographer is not known.
Blizzards
• Is a heavy snowstorm
with winds of more
than 35 miles per
hour and reduced
visibility.
• Some areas because
of their location will
received as much as
37.5 feet of snow per
year.
Droughts
• A long period of time
without rain or with
very minimal rainfall.
• Makes in hard on
crops & results in
reduced levels in
water storage.
• 1930s, the Great
Plains were known as
“Dust Bowl” as
150,000 square-mile
were hit with dust
storms.
Floods
• When water spreads
over land not normally
covered with water.
• Melting snow or
rainwater will fill rivers
until they reach a
flood stage.
• After a river cannot
take water any more it
will flows into
surround areas called
floodplain.